How long is the longest day where you live?
Pick a town and see how many hours of daylight it gets on the longest and shortest days of the year, when the sun rises and sets, and how it compares with eight towns from Kaitaia to Invercargill. Calculated from the sun’s position, not looked up, so it works for every town in New Zealand.
Times are local clock time, with daylight saving applied where it is in force on that date.
Auckland
Longest day against shortest day
Each bar runs from the shortest day’s daylight to the longest day’s. The further south you go, the wider the bar.
Daylight through the year
Hours of daylight for every day of the year. Click a name in the legend to remove it.
The numbers
| Town | Latitude | Longest day | Sunrise | Sunset | Shortest day | Sunrise | Sunset | Swing |
|---|
Longest and shortest days are found by calculating every day of the current year and picking the maximum and minimum. Daylight is sunrise to sunset with the standard allowance for refraction. Turn on civil twilight to add the usable light before sunrise and after sunset, when the sun is less than 6 degrees below the horizon.
Why the south gets more summer and less winter
The Earth’s axis is tilted about 23.4 degrees, so as it moves around the sun each hemisphere leans toward the sun for half the year and away for the other half. The further you are from the equator, the bigger the effect. At the equator every day is close to 12 hours long. In Invercargill, 46 degrees south, the sun is up for almost 16 hours in late December and barely eight and a half in late June. Kaitaia, 11 degrees of latitude further north, has a swing of only about four and a half hours.
The dates shift slightly from year to year. The December solstice falls on 21 or 22 December and the June solstice on 20, 21 or 22 June, and the longest and shortest days of daylight land on or beside those dates. Sunrise and sunset do not move in step with each other. The earliest sunrise of the year comes a week or so before the December solstice and the latest sunset a week or so after it, because of the slight wobble in the sun’s clock time known as the equation of time. That is why the evenings keep stretching into early January even though the days have started to shorten.
Daylight saving
New Zealand’s clocks go forward one hour at 2am on the last Sunday in September and back again at 3am on the first Sunday in April. The change does not add any daylight, it moves an hour of it from the morning to the evening. All the times here apply daylight saving automatically for dates when it is in force. The Chatham Islands keep their own time, 45 minutes ahead of the mainland, and that is applied too.
How this is calculated
Sunrise, sunset and day length come from the standard solar position equations published by the US National Oceanic and Atmospheric Administration, using each town’s latitude and longitude. Sunrise and sunset are the moments the top edge of the sun crosses the horizon, allowing for atmospheric refraction, which is the definition almanacs use. The figures are accurate to within about a minute for any town on flat ground. Hills, buildings and the horizon at sea can move the moment you actually see the sun by several minutes, and cloud does what it likes. Town coordinates are the centre of each town.